Air moving apparatus



March 5, 1935. M. FUNK 1,993,158

AIR MOVING APPARATUS Fi'led Sept. 8, 1930 2 Sheets-Sheet 1 IN V EN TOR.

1 ATTORNEY March 5,1935. JFUNK 1,993,15s-

AIR MOVING APPARATUS -Filed se Ls, 1950 I 2 Sheets-Sheet 2 IIiVgENTOR.waWe M A TTORNEYS.

Patented Mar. 5, 1935 PATENT OFFICE 1,99s,15s AIR MovnmI APPARATUS JamesM. Funk, Rockford, Ill., assignorto George D. Roper Corporation-Application September 8,1930, Serial No. 480,422

8 Claims.

the upstream diameter being greater than the propeller diameter, and thecenter of lift of the aerofoil at the propellers tip being forward ofthe entering edge of the shroud.

One application of the invention is illustrated in the accompanyingdrawings wherein the principle involved is shown in connection with aheater. It should be clearly understood, however, that this adaptationis merely illustrative and must not be construed as a limitation of theuses to which the invention" can be put.

In said drawings: Y

Fig. 1 is a view in rear elevation of a hot water heat radiator equippedwith. the invention;

Fig. 2 is a view in vertical section, taken on the line 2-2, Fig. 1;

Fig. 3 is a detail view in cross-section of an aerofoil member which hasbeen selected as an aid in describing the principle of operation of theinvention, and r Fig. 4 is a diagrammatic drawing showing inflow andoutflow air currents and the novel effect secured with the shroud of myinvention,

. whereby the air handling facility of the air screw propeller isgreatly increased.

In my Patent Number 1,327,543, issued January 6, 1920, I have shown howit is possible to increase the air handling facilities of an aeroplanepropeller by the use of a shroud structure used in combination withcertain controlling elements.

- From actual experiments and tests made it has been proven that apropeller, fan or the like when given the benefits of a properlydesigned shroud structure will function to far better advantage and thisis true when the propeller is used, as such or when it becomes a fan orblower.

In my patent above identified I have shown a so called variable pitchshroud located in a certain predetermined relation to the propeller. Inthe present invention the location of the shroud with respect to thepropeller is changed so as to cut ofi parasitic currents whose badeffect upon performance was not realized in the previous central openingsubstantially corresponding to construction and consequently were notbaifled as they are in the present structure. Furthermore, in accordancewith the present invention, the variable characteristics of the shroudare discarded in favor of a rigid non-adjustable con- 5 struction whichadapts it better to use with fans, blowers and the like, although it isstill well adapted to use with propellers on'aeroplanes.

Referring now to the drawings in detail, 5 represents a four bladed airscrew pr peller of 10 a'tvp cent, designed for use in connection withhe. anc.....crs such as hot water heat radiators'. According to thepresent showing the fan 5 is mounted by its hub 6 direct to the shaft '7of an electric motor 8. The base9 of the air 15 screw propellers motoris supported upon a pedestal like structure 10 which includes adownwardly depending arm 11 and a cross rod 12. The lower end of the arm11 and opposite ends of the cross rod 12 are bolted or otherwisefastened to the housing 13 for the radiator core 14. The housing 13 maybe stamped from sheet metal or constructed in any other way suitable forthe purpose. In any event it will be made with a the diameter of thepropeller fan. In thepresent instance it is of four corner design havingrearwardly extending surrounding walls of a depth to hold the radiatorcore 14 in proper spaced re?- lation in front of the propeller.

With such a heater assembly rotation of the fan 5 will force air throughthe radiator core 14 and with hot water or other heat medium circulatingthrough the core sections a hot air blast will be realized'in front ofthe heater.

It isth'e purpose of my invention to increase the air handling facilityof the air screw propeller 5 as previously mentioned and I propose toaccomplish this objective primarily with the aid of a fixed shroudstructure represented as at 14'. 40 The same being preferablyconstructed of pressed sheet metal and disposed in the central openingin the front of the housing 13 surrounding the fan blades 5'. The formand proportioning'of the shroud 14', as well-asits particularrelationship to the propeller -5 are. most important. First of all, itwill be observed that it is circular in form and concentric with thepropeller 5, the tips of the propeller blades being disposed in closeproxir'hity to the inside of the shroud (see Fig. 2). Next, it will beobserved that the shroud-is of tapered or funnel shape with the trailingedge relation to the entering and trailing edges of the shroud is alsoimportant; the center of lift of the aerofoil at the tips of the bladesis forward of the entering edge of the shroud. In other words, the

shroud is conformed to the propeller to provide at the propellers tipsbeing forward of the entering edge of the shroud. The propeller 5, beingan air screw propeller, is properly referred to as an aerofoil, as thoseskilled in the art are well aware, and the design of the shroud is basedfrom start to finish on the presumption that the part 5 is an air screwpropeller, inasmuch as an ordinary fan, as that term is generally takento imply, will not give the results which this invention was designed toproduce. Regardless of the characteristics of each particular propeller,the above statement as to the form and relationship of the shroud to thepropeller applies, but it will be understood that a specific shroudangle, shroud trailing diameter and distance of termination downstreamfrom the trailing edge of the propeller is demanded for each change ingeometrical proportions of the propeller, these angles, diameters anddistances being figured mathematically in relation to the propeller forwhich the particular shroud is being designed.

Referring now to Fig. 4, I shall explain by reference to this diagramthe actual performance of the shroud 14 and that portion of the shroudreferred to as the nosing 16. In this view, the arrows indicate airstreams and are shown on a line corresponding with the distance in frontof the propeller equal to .125 times the diameter and a distance behindthe propeller equal to .0625 times the diameter, as well as in theimmediate vicinity and around the periphery of the propeller. The airstreams, with which this invention is most concerned, are .those markedA, T, 1, 2, and 3. The angle of these arrows and their length indicatethe direction of the flow in relation to the propeller disc and therelative velocities. The arrow T indicates air drawn or pulled in by thepropeller through the lateral tips and commonly referred to as theradial flow. The other arrows at right angles to the propeller arecommonly referred to as the axial flow. It will be noticed that arrows1, 2 and 3 are pointed in counter-flow and that they are the terminationof streams originating in front of the propeller. This is due to thefact that the propeller, as illustrated in Fig. 3, being an aerofoil,produces a positive pressure under the blade and a negative pressure ontie upper surface of the blade and at the lateral tip the air thus putunder pressure flows -around the tip into the lower pressure area abovethe blade, thus producing a turbulence, as

' is illustrated by the arrows and dotted lines.

In Fig. 8, the aerofoil is numbered 5 to correspqnd to the propeller. At20, are indicated the air streams striking the face 21 of the propellerand deflected therefrom in an area of positive pressure. The streams 1'7striking the edge 18 are divided, part. going into the pressure area,and the rest into the negative pressure area on the back of the blade.The shroud of my invention deals with the turbulence and prevents thewall of the housing.

eter than the disc swept out by the propeller blades. The exact positionof the propeller with parasitic air streams numbered 1, 2 and 3, fromreturning into the propeller tip. The area between the tips of thepropeller and the shroud is under suction, the suction being produced bythe action of the propeller as illustrated in Fig. 3. This suctionmanifests itself by bending the line A and line T at the nosing 16 inthe manner shown, which means that more air is drawn in and is handledby the propeller without increasing the horsepower absorbed. The airindicated by lines 1, 2, and 3 are velocity pressures translated intostatic pressure by impact with the inside of the back wall of thehousing 13 or for the sake of this illustration the part numbered 15 inFig. 4, it being obvious that the portion 15 is, to all intents andpurposes, a part of the rear The static pressure thus developed resultsin the movement of air through the four corners of the core 14. In otherwords, the area of the propellers effective outflow is actually greaterthan the diameter of the propeller. The line T should now be notedbecause it is most important in regard to the nosing 16, according tothe principle laid down by Otto Lillienthal on the forward and uppersurface of an aerofoil, a partial vacuum or lower pressure is producedby the phenomena of air motion. This suction on the upper surface hasthe effect of increasing the magnitude of the air streams indicated byline T. Increasing line T means an increase in the mass of air movedthrough the propeller pressure in the outflowing stream. The importanceof this in the case of a heater such as that herein shown can be easilyappreciated. In the case of an aeroplane, it means an increase in thrustso that the aeroplane gets off in a shorter run. In conclusion,therefore, it will be seen that the shroud not only converts what wouldotherwise be parasitic reactions to beneficial results, that is, by thebaflling of currents 1, 2, and 3, but also draws in more air by reasonof the action of the nosing 16, that is, by increasing streams A and T.

Another feature which is of importance so far as the present heater isconcerned resides in the novel stream-line design of the core sections25. A core section designed as shown will function with two advantageousresults. First, the air lines will completely'embrace and scrub theentire surface area ofthe sections and from end to end and as a resultmore air will contact with the sections-and thus create a. moreeffective heat transfer. Furthermore, the hot water, steam, or gasescirculating through a stream-line core section will be spread out insuch a manner as to present maximum area for radiation purposes.

The design selected for illustrating the invention is especially adaptedfor unit heaters and coolers but as previously stated this illustrationis not to be taken as a cation of the invention as it will also find agood field of usefulness in othgil'1 air handling apparatus, of whichthe most portant worth mentioning are propellers for aeroplanes.

limitation of the applidisc and in consequence increases the Having thusdescribed and shown an embodiment of this invention, what I claim anddesire angle to the axis of rotation of the blades and face at an angleto the" axisof rotation thereof terminating in a trailing edge of lessdiameter than the disc swept out by the blades, the leading annular edgeof said shroud structure being of greater diameter than the aforesaiddisc and having a curved nose portion so situated with respect to thepropeller to serve as an aerofoil for causing radial inflow to the tipsof the blades.

2. An air moving apparatus comprising in combination, an air screwpropeller havinga plurality of rotatable blades, and a continuousannular shroud structure fixedly mounted with its inner surface arrangedto extend across the tips of the blades at an oblique angle to the axisof rotation of the blades and terminating be-' yond the trailing edgesthereof in a diameter slightly less than the propeller diameter, thelead ing annular edge of said shroud structure being disposed in theplane of the center of the propeller's lateral tips and of a diameterslightly larger than that of the propeller.

3. An air moving apparatus comprising in combination, an air screwpropeller having a plurality of rotatable blades, and a shroud structuresurrounding said blades with its inner surand extending across the tipsof the blades, originating in a curved nose at its leading edge of adiameter greater than that of the propeller and with a trailing edge ofless diameter than that of the propeller, said curved nose beingdisposed in the plane of the center of the propellers lateral tips, andbeing so formed whereby the same serves as an aerofoil for causingradial inflow to the tips of the blades.

4. An air moving apparatus comprising, in combination with the wall of ahousing having a central opening provided therein, an air screwpropeller having a plurality of rotatable blades, and a shroud structuresurrounding said blades having the inner surface thereof at an angle tothe axis ofrotation thereof, the shroud originating in a curved nose atits leading edge and with a trailing edge of less diameter than thediameter of the disc swept out by the rotation of the blades, saidshroud having its leading edge provided with the rounded nose projectingfrom the wall of the housing and of a diameter greater than that of thepropeller, said nose portion being so disposed with respect to thepropeller to serve as an aerofoil for causing radial inflow of air tothe tips. of the blades.

5. In an air handling device, the combination of an air screw propellerof a certain diameter and an annulus surrounding only the disc swept 55out by the propeller, said annulus being in close nInm-n- A a mproximity to the tips of the blades oisaid pro-' peller, said annulusbeing formed to provide an evase discharge and venturi in the downstreamarea of less diameter than that of the propeller, and being formed toprovide a projected angle aero'foil in the upstream area of greaterdiameter than that of the propeller, said annulus being so disposed thatthe leading edge is in the same plane with the center of the lateraltips of the blades of said propeller.

6. An air moving apparatus .comprising in combination, an air screwpropeller having a plurality of rotatable blades, and an annular shroudstructure having an inner surface providing a working face extendingacross the tips of the blades at an oblique angle to the axis ofrotation of the blades, said shroud having its leading edge of greaterdiameter than the disc swept out by the blades and terminating in, atrailing edge of less diameter than the diameter of the disc swept outby the rotation of the blades, the leading annular edge of said shroudstructure being disposed in the plane of the center of the propellerslateral tips.

7. An air handling apparatus comprising, a housing through which air isto be passed, an air screw propeller having a plurality of blades forpropelling the air through said housing,. an end plate for said housinghaving a central opening in which said blades revolve, and anannularshroud for said blades in said opening and having an inner surfaceextending across the tips of the blades at an oblique angle to the axisof rotation of the blades, the shroud terminating in trailing relationto the propeller in a diameter less than that of the propeller, theentering edge of said shroud being of a greater diameter than that ofthe propeller and disposed in the same plane with the center of thelateral tips of the blades of said propeller.

8. An air moving apparatus comprising in combination, an air screwpropeller having a plurality of rotatable blades, and a continuousannular shroud structure fixedly mounted with its inner'surface arrangedto extend across the tips of the blades at an oblique angle to the axisof rotation of the blades and terminating beyond the trailing edgesthereof in a diameter approximately nine-tenths of the propellerdiameter, the leading annular edge of said shroud structure beingdisposed in the plane of the center of the propellers lateral tips andof a diameter approximately 1.2 times the propellers diameter.

- JAMES M. FUNK.

cenrrrlcnrn or CORRECTION Patent No. 1.993,l58. March 5. 1935.

JAMES M. FUNK It is hereby certified that the above numbered patent waserroneously issued to "George D. Roper Corporation"as assignee of theentire interest in said invention whereas said patent should have beenissued to the inventor said "Funk" as shown by the records of the casein this office; and that the said Letters Patent should be read withthis correction therein that. the same may conform to the record of thecase in the Patent Office. I

Signed and scale this 18th day of June,- A. D. 1935.

Les I it: Frazer K Acting Commissioner of Patents.

